Polyester fiberfill is used commercially in many garments and other articles because of its desirable thermal insulating and aesthetic properties. Polyester fiberfill is generally used in garments in the form of bulky quilted batts. Most commercial polyester fiberfill has been in the form of crimped polyester staple fiber.
It has generally been considered desirable to maximize the bulk of the polyester fiberfill in the form in which it is eventually used, e.g. in a garment, since it has been found that increasing the bulk (or loft), and the durability thereof, increases the thermal insulation provided by the polyester fiberfill in the garment. It has, therefore, become conventional, for many purposes, to provide the polyester fiberfill with a coating of durable (i.e. wash-resistant) silicone slickener (cured polysiloxane), e.g. as disclosed in Hofmann U.S. Pat. No. 3,271,189 and Mead et al U.S. Pat. No. 3,454,422, because this provides the resulting articles with certain desirable properties, such as bulk-stability and fluffability. Most slickened and unslickened polyester fiberfill used in garments has generally been of denier about 5-6. An important reason is because it has been found that such denier has provided optimum bulk in use. Another prior suggestion for improving bulk has been the use of hollow polyester fiberfill, e.g. as disclosed in British Pat. No. 1,168,759 and Tolliver U.S. Pat. No. 3,772,137. Commercial use of hollow polyester fiberfill has increased significantly in recent years.
Research Disclosure Journal (September 1975) Article No. 13717, page 14, discloses the inclusion in polyester fiberfill of a specific low-melting-point binder fiber, poly(ethylene terephthalate/isophthalate), and its bonding to improve the stability and handling characteristics of the fiberfill, e.g. in batts, including batts to which polysiloxane slickeners have been applied. Mixtures of polyester fiberfill with lower melting binder fiber are also suggested elsewhere, e.g. in Scott U.S. Pat. No. 4,129,675, which discloses forming a web having a central band made from silicone-slickened polyester hollow fiberfill and outer bands made from a blend of unslickened hollow polyester fiberfill and binder fiber, and forming a batt having a center layer of such silicone-slickened polyester fiberfill and upper and bottom layers of said blend. Stanistreet U.S. Pat. No. 4,068,036 suggests the use of conjugate or bicomponent fibers for use as binder fibers in fiberfill blends.